The event began without incident until after 6 p.m., when members of Patriot Prayer took to the streets following their gathering in Portland's Terry Schrunk Federal Plaza, the Oregonian reported.

Patriot Prayer's organizer is Joey Gibson, a U.S. Senate candidate in Washington state, the newspaper reported, adding that the group is based in Vancouver, Wash., located just across the Columbia River from Portland.

Tensions escalated as the two groups heckled each other, the report said. Antifa members began lobbing eggs, half-empty water bottles, and firecrackers. Others in the crowd lit firecrackers and smoke bombs.